Classe CP50 or CP47.5?

The above is true except that the 47.5 replaced the CP45.
it was a step up from the CP35. I think that they intended
it to be a replacement for the CP50 but like was stated
above NO WAY.Also the phono boards for the CP35,45 and 45.7
are not the same as the one for the CP50 and 60.

When did the CP50 came out?

I believe the CP50 came out about five years ago together with the Classe CA line of power amps. Those were the days when Classe products held up the best performance/dollar values. Since the introduction of Omega and the CA 01 series of power amps, every Classe model went up in price. I understand Classe discontinued the CP50 and 60 pre-amps to make way for the Omega and Omicron pre-amps which sell for way more than the CP50's and 60's. Let your ear be the judge ! I'm a CAM350 power amp owner and I still hang on to my CP50 !